Process for 3-keto-delta4,6 steroids



United States Patent Claims priority, application Mexico Aug. 8, 1961 Claims. (Cl. 260397.4)

The present invention relates to a novel process -for the production of cyclopentano phenanthrene derivatives.

More particularly the present invention relates to a novel process for the production of 3-keto-u -derivatives of the androstane and pregnane series from the corresponding 3-enol ethers. f

Several methods have been used in the past for the introduction of a double bond at the 5,6 position. Among these therehas been disclosed a method which comprises treating a 3-keto steroid with a qui'none in a high boiling point solvent at a temperature higher than 100 C. (Agnello and Laubach, US. Patent 2,882,282).

The process disclosed in this patent has several disadvantages due in part to the high temperatures used and in many instances gives relatively low yield. This is especially true when there is present in the C-6 position a halogen or methyl substituent in either the on or 8 positions.

In accordance with the present invention the surprising discovery has beenmade that 2,3-dichloro-5,6-dicyano 1,4-benzoquin0ne (D.D.Q.) will readily react with enol ethers derived from A -3-lceto steroids at low temperature to give quantitative yields of the corresponding A -compounds. Further, this is true whether or not there is present a 6-substituent such as halo or lower alkyl.

The present novel process may be exemplified by the following equation:

Il I R I Q ma Q H+ RO- Q Y j X X I II In the above equation R is a hydrocarbon residue such as alkyl, aryl or aralkyl, preferably a lower lalkyl; R may be hydrogen or methyl; X represents hydrogen or a substituent such as fluorine, chlorine, bromine or lower alkyl which are often in the C-6 position throughout the steroid art, or other less common substituents that do not hinder the reaction as for example chloromethyl, difluoromethyl, etc.

In practicing the above outlined process the 3-alkoxy- A starting steroid (I) is treated with approximately 1 molar equivalent of a benzoquinone with an oxidation 7 potential of less than O.75 v., preferably 2,3-dichlororeaction, although this is not necessary. In one ofthe methods the second step consists in diluting the filtrate with a solvent not miscible with water and subsequently washing the mixture with a dilute aqueous basic solution as for example 5% aqueous sodium hydroxide solution until the washings are colorless, which is an indication of the absence of undesired hydroquinone in the solution. Conventional working up of the organic layer such as drying, evaporation and purification of the residue ailords the pure final product.

A second method of isolation consists infiltering the reaction solution as such, or diluted with a slightly polar solvent such as methylene chloride, through an adsorbing material such as alumina and subsequently eluting the product with :a suitable solvent. By conventional working up the resulting solution yields the desired 3-ke tor hated hydrocarbons such as: chloroform, methylene dichloride, ethylene dichloride and other non-basic solvents inert to the said reagent, known to the skilled in the art.

The catalyti'c amount of acid previously mentioned may vary from 0.001% to 10% in weight of the total reaction mixture. Acids that may be used in the present process include mineral acids and strong organic acids such as: p-tol-uenesulfonic acid, gaseous hydrogen chloride or bromide, acetic acid and propionic acid.

For optimum production of 3-keto-A steroids (II) it is preferred to use a quantity of the aforementioned quinone reagent as near as possible to 1 molar equivalent, for an amount substantially inferior would lead to the formation of mixtures of starting and final compounds, anexcess reagent would produce mixtures of 3 keto-A and 3-keto-A steroids.

Satisfactory yields are obtained when the reaction is carried out within the hereinbefore defined temperature and time limits, but optimum results are obtained at approximately 0 C., the duration of the reaction being of about 30 minutes.

3-alkoxy-A -androstane or pregnane derivatives are in general suitable starting materials for the present dehydrogenation process. There may be present in the molecule a variety of substituents without affecting the reaction in any Way. These substituents, which consequently would be present in the final products, may be, for example, rat the 2, 6, 9, '11, 14, 15, 16 and 17 positions. For instance, ketonic groups may occur at the 11 and/ or 20 positions, hydroxyl groups at the 9, 11, 14, 15, 16, 17 and/or 21 positions, halogen atoms at the 2, 6, 9, 11, 16, and/or 21 positions, alkyl groups at the 2, 6, 16 and/or 17 positions, double bonds at the 8, 14, 16 or 9(11) positions, etc. Among the compounds which can be prepared by the present process are: 6-chloro-A -pregnadien- 17a-o-l-3,20-dione-17-acetate, 6 chloro-A -androstadien- 17B-ol-3-one, 6-methyl-l9-nor-A androstadien-175-01-3- one, A androstadien l7,8-ol-3 one, 6-fluor0-A -androstadien-17,8-ol-3-one-17-propionate, 6 iluoro-l9-nor-A pregnadien-17u-ol-3,20-dione, 6-fl11oro A pregnadien- 17a-ol-3,20-dione, A -pregnadien-17a-ol-3,20-dione, A pregnadien-17a,21-diol-3,1 1,20 trione, 6-fluoro-A -pregnadien-17u,21-diol-3,11,20-trione, 6-fluoro A pregnadien-l 113,17u,21-triol-3,20 dione, 6,9'a difluoro-h pregnadien-17a,21-diol-3,11,20-trione, 6-chloro A pregnadien-l7a,21-diol-3,11,20-trione, 6-chloro c fiuoro-h pregnadien-l1,8,17a,21-triol-3,20-dione-21-acetate, 6,165-

ti-ves which are potent anabolic agents, as for example 6-chloro-A -androstadien-l7B-ol-3-one and 6-flu0ro-A androstadien-l7fl-ol-3-one.

The following specific examples serve to illustrate but are not intended to limit the scope of the present invention.

Example 1 A suspension of 1 g. of 6a-chloro-A -pregnen17a-ol- 3,20-dione-17-acetate, in 7.5 cc. of anhydrous peroxide free dioxane was treated with 1.2 cc. of freshly distilled ethyl orthoformate and 0.8 g. of p-toluenesulfonic acid. The mixture was stirred at room temperature for 15 minutes and the resulting solution let stand for 30 minutes further. 0.8 cc. of pyridine were added and then water. The formed precipitate was collected by filtration, water washed and air dried. Recrystallization from acetonehexane afforded 6-chloro-3-ethoxy-A -pregnadien-1704-01- 20-one-17-acetate with a melting point of 175176 C.

Example 2 A solution of 1 g. of the foregoing 3-ethyl enol ether in 20 cc. of tetrahydrofu-ran was cooled to C. and there were added 1.05 molar equivalents of 2,3-dichloro- 5,6-dicyarro-1,4 benzoquinone and 100 mg. of p-toluenesulfonic acid. The resulting mixture was further stirred at 0 C. for 30 minutes. The precipitated hydroquinone was filtered oil and 100 cc. of methylene dichloride were added to the filtrate.

The organic solution was then filtered through 30 g. of alumina, the filtrate was evaporated to dryness and the residue crystallized from acetone-hexane thus furnishing the desired 6-chloro-A -pregnadien-17wol-3,20-dione-17- acetate in 75 yield, this compound had a melting point of 209-211" C.

Example 3 A solution of 1 g. of 6-c-hloro-3-ethoxy-A -pregnadienl7a-ol-20-one-l7-lacetate in 20 cc. of tetrahydrofuran was cooled to 0 C. and there were added 1.05 molar equivalents of 2,3-dichloro-5,6-dicyano-1,4 benzoquinone and 100 mg. of p-toluene-sulfonic acid. The resulting mix ture was further stirred at 0 C. for 30 minutes. The precipitated hydroquinone was filtered off and 100 cc. of methylene dichloride were added to the filtrate. The organic solution was washed with 5% aqueous sodium hydroxide solution until the washings were colorless, then with water to neutrality, dried over anhydrous sodium sulfate and evaporated to dryness. Crystallization from acetone-hexane gave 6-c=hloro-A -pregnadienl7a-ol-3,20- dione-17 acetate, in a 76% yield.

Example 4 1 g. of 6-ehloro-3-ethoxy-A -pregnadien-17a-o-l-20-one 17-acetate was treated following the technique described in Example 3 except that the reaction was carried out at i+10 C. for 25 minutes thus furnishing 6-chloro-A pregnadien-17ot-ol-3,20-dione-17 acetate, in 70% yield.

Example 5 p 1 g. of 6-cl1loro-3-ethoxy-A -pregnadien-l7a-ol-20-one- 17-acetate was treated by the procedure described in Example 3 except that the reaction was made at -20 C. during 3 hours giving 6-chloro-A -pregnadien-17a-ol- 3,20-dione-17-acetate, in 70% yield.

Example 6 1 g. of 6-chloro-3-ethoxy-A -pregnadien-17u-ol-2O-0ne- 17-acetate was treated in accordance with the procedure delineated in Example 3 except that the reaction occur-red at -40 C. for 24 hours affording 6-chloro-A -pregnadien-l7c:-0l-3,20-di0ne-17-acetate, in 50% yield.

Example 7 In accordance with the method described in Example 2 except that tetrahydroturan Was substituted by methylene chloride, there was obtained the same product in 74% yield.

Example 8 By substituting tetnahydrofuran by toluene in Example 3 there was obtained the desired product in 75% yield.

Example 9 Acconding to the method described in Example 4 except that tetrahydrofuran was substituted by dioxane, there was obtained the same pro-duct in 75% yield.

Example 10 1 g. of 6-chloro-3-ethoxy-A -pregnadien-1704-01 20- one-l7-acetate was treated following the procedure described in Example 3 except that instead of adding mg. of p-toluene-sulfonic acid to the reaction mixture, there was passed a current of gaseous hydrogen chloride during 30 seconds thus yielding 6-chloro-A -pregnadieno 17a-ol-3,20-dione-17-acetate in 74% yield.

Example 11 The A -3-ketones listed below were converted into the corresponding 3-enol ethers hereinafter set forth, following the technique described in Example 1 and using the indicated alky l orthoformate.

Starting compound allryl Product orthoiorrnate 6a-chloro-tcst0sterone methyl ortho- 6-chlor0-3-methoxy-A -aniormate. drostadien-Nfi-ol. 6a-ehloro-19-nor-testosterethyl ortho- 6 ehloro 3 ethoxy 19 nor one. formate. A -androstadien17f3-ol. Gal-methyl 19-nor -testospropyl ortho- 6-methyl-B-propoxy-lQ-norterone. formats. A -androstadiemUfl-ol. Testosterone ethyl ortho- 3-ethoxy-A -androstadienformate. 178-01. fia-flllOlO testosterone 17- methyl ortho- 6-fluoro-3-methoxy-A -anproprionate (U.S. Pat. formate. 2,838,492).

6a-fluoro-l7a-hydroxy-19- nor-progesterone (U.S. Pat. 2,838,495).

drostadien-17fi-ol-17-propionate. 6-fluoro-3-propoxy-19-nor- A -pregnadien-l7a-ol-20- propyl orthoiormate.

one. methyl ortho- 6 fluoro 3 -rnethoxy A 63 fluoro hydrocortisone propyl ortho- 6 fluoro 3 propoxy A (U.S. Pat. 2,838,497). lormate. pregnadiene-llfi, 17, 21-

triol-20-one. 6a a-difluorocortisone methyl ortho- 6, 9a difiuoro -3 -metl10xy- (U.S. Pat. 2,838,498) formate. A -pregnadiene-17a,21-

diol-ll, 20-dione. (Sfl-chloro-cortisone (Rinethyl ortho- 6-eh1oro-3-ethoxy-A -pregold et a1., JACS 80, form-ate. nadiene-l7a,21-diol-1l,20-

cortisone 21 acetate (Ringold et a1., JACS dione 6 chloro 9m fluoro 3 propotty-A -pregnadien-llfi, 17a, 21-triol-20ene-21-acetate. 6, 16,8 dimethyl 3 ethoxypropyl orthoiormate.

6a,lfifl-dimethyl-hydrocorethyl orthotisone. formate. A -pregnadienedl i, 17a,

21-triol-20-one.

Example 12 Following the technique described in Example 3 there the corresponding products hereinafter disclosed.

Starting compounds Products ta 6,1613-din1ethyl-A fi-pregnadien-llfi,

17a, 21-triol-3,20-dione.

Example 13 1. g of. 6-chloro-3-ethoxy-A -pregnadien-17u-ol 20- one-17-acetate was treated in accordance with the procedure described in Example 2, except that 2,3-dichloro-5,6- dicyano-1,4-benzoquinone was substituted by tetrachlorm or-tlio-benzoquinone, thus yielding 6-ch-loro-A -pregnadien-l7a-ol-3,20-dione-l7-acetate, in 65% yield.

Example 14 1 g. of 6-chloro-3- ethoxy-A -tpregnadiien-17w-ol 20 one-17-acetate was treated in accordance with Example 2, but 2,3-difluoro-para-benzoquinone was used instead of 2,3-dichloro-5,6-dicyano1,4 benzoquinone, thus furnishing 6-chl0ro-A -pregnadien-17u-ol-3,2O-dione 17-acetate, in 64% yield.

. Example 16 6-c'hloro-3-ethoxy-A -pregnadien-i7oc-o1-20 one '17- acetate was treated according to Example 3, except that 2,3-dichloro-5,6-dicyano-1,4-benzoquinone was substituted by 2,3-dibenzoylpara-benzoquinone, thus affording 6- chloro-A pregnadien-17or-ol-3,20edione-17 acetate in 62% yield.

We claim: 7

1. A process for the production of 3-keto-A -steriods selected from the group consisting of the androstane and pregnane series which comprises treating a 3-enol ether- A -steroid with a benzoquinone with an oxidation potential of less than -0.75, in a solvent inert to the reagent and in the presence of a'catalytic amount of acid to form the corresponding 3-keto-A -steroid.

2. The process of claim 1 wherein the amount of said benzoquinone is approximately 1 molar equivalent.

3. The process of claim 1 wherein the inert solvent is selected from the group consisting of aromatic solvents.

4. The process of claim 1 wherein the inert solvent is selected from the group consisting of chlorinated lower hydrocarbons.

5. The process of claim 1 wherein the inert solvent is tetrahydrofuran.

I 6. A process for the production of 3-keto-A -steroids selected from the group consisting of the androstane and pregnane series which comprises treating a 3-eno1 ether- A -steroid with a benzoquinone with an oxidation po tential of less than 0.75, in an inert solvent and in the presence of a catalytic amount of acid for a period of time of from about 25 minutes to about 24 hours at a temperature within 40 C. to +10 C. to form the cor- (responding 3-keto-A -steroid.

7. The process of claim 6 wherein the inert solvent is tetrahydrofuran, the period of time is of around 30 minutes and the temperature is approximately 0 C.

8. The process of claim 6 wherein the benzoquinone is 2,3-diohloro-5,6-dicyano-1,4-benzoquinone.

9. The process of claim 7 wherein the benzoquinone is 2,3-dichloro-5,6-dicyano-1,4+benzoquinone.

10. The process of claim 9 wherein the starting steroid is 6-chloro-3-ethoxy-A -pregnadien-17a-o1-20-one 17- acetate and the final 3-keto-A -steroid is 6-chloro-A pregnadien-l7or-ol-3,20-dione-17-acetate.

No references cited. 

1. A PROCESS FOR THE PRODUCTION OF 3-KETO-$4,6-STERIODS SELECTED FROM THE GROUP CONSISTING OF THE ANDROSTANE AND PREGNANE SERIES WHICH COMPRISES TREATING A 3-ENOL EHTER$3,5-STERIOD WITH A BENZOQUINONE WITH AN OXIDATION POTENTIAL OF LESS THAN -0.75, IN A SOLVENT INERT TO THE REAGENT AND IN THE PESENCE OF A CATALYST AMOUNT OF ACID TO FORM THE CORRESPONDING 3-KETO-$4,6-STEROID. 